Alright, I have a project ahead. I am going to be installing 6x9's in the rear decklid of a 5th generation Camaro.
The stock speakers ALREADY cause some rattle when you get some bass thumping. This can be seen here:
2010 Camaro Boston Speakers - YouTube
I know how to bolt things up and plug them in, but controlling rattles is beyond my knowledge base. To install the 6x9's in this car, it requires you remove the back seat, and all the paneling from the seatbelt back. It's a royal PITA that I don't want to have to do twice, so I want a plan of attack here.
This leads me to my question. What's the best way to control this type of rattle?
I know a lot of times people automatically think Dynamat. I did, because this is what it's been marketed as. It's the solution to every problem! Road noise? Dynamat. Rattle? Dynamat. Panel vibration? Dynamat... Spend more than a few minutes on the internet car forums and the more boutique branded Second Skin will be recommended. It's better made stuff than Dynamat, but it's Damplifier (Pro) is still compressed-layer damping.
Is it really the solution? I'm not sure.
And while I am asking about it, I want to learn a bit if I could. The theory of CLD's is that you bond a viscoelastic material (in the case of high quality brands this is a butyl rubber compound), to the substrate (aka the car, be it the floor, trunk, or in my case decklid/parcel shelf), and with a constraining layer a-top (in the case of high quality brands this is >4mil thick aluminum foil).
So, bottom layer = car, middle = butyl rubber, top = aluminum foil. Apparently it works because the low frequencies of the speaker cause the substrate to flex/resonate, causing shear strains to develop in the viscoelastic butyl rubber.
What I don't understand is the importance of the constraining layer (the aluminum foil), and specifically the importance of it's thickness. If the shearing and energy exchange happens in the butyl, why is it beneficial to have a thicker constraining layer? This is the major difference in pricing when comparing brands. It's all about the thicker constraining layer. It's what differentiates Second Skin's Damplifier and Damplifier Pro products.
Is the thicker constraining layer just doing the job of mass loading? When speaking in terms of mass loading, I was under the impression that it was it's own product, typically taking the form of Vinyl loaded with Barium Sulfate.
I really hate how there is so much misinformation and general lack of information when it comes to WHY these sound deadening/damping products work.
I mean heck, over a different camaro centric forum, I've read about folks using bungee cords to pull down on their decklid to stop it from rattling. I've read about folks screwing up from the bottom of the decklid into the speaker mounting bracket. Everyone seems to have some "trick" or band-aid, and I just want to do this the RIGHT way.